Upregulated microRNAs in membranous glomerulonephropathy are associated with significant downregulation of IL6 and MYC mRNAs

Membranous glomerulonephropathy (MGN) is a glomerulopathy characterized by subepithelial deposits of immune complexes on the extracapillary side of the glomerular basement membrane. Insertion of C5b-9 (complement membrane-attack complex) into the membrane leads to functional impairment of the glomerular capillary wall. Knowledge of the molecular pathogenesis of MGN is actually scanty. MicroRNA (miRNA) profiling in MGN and unaffected tissues was performed by TaqMan Low-Density Arrays. Expression of miRNAs and miRNA targets was evaluated in Real-Time polymerase chain reaction (PCR). In vitro transient silencing of miRNAs was achieved through transfection with miRNA inhibitors. Ten miRNAs (let-7a-5p, let-7b-5p, let-7c-5p, let-7d-5p, miR-107, miR-129-3p, miR-423-5p, miR-516-3p, miR-532-3p, and miR-1275) were differentially expressed (DE) in MGN biopsies compared to unaffected controls. Interleukin 6 (IL6) and MYC messenger RNAs (mRNAs; targets of DE miRNAs) were significantly downregulated in biopsies from MGN patients, and upregulated in A498 cells following let-7a-5p or let-7c-5p transient silencing. Gene ontology analysis showed that DE miRNAs regulate pathways associated with MGN pathogenesis, including cell cycle, proliferation, and apoptosis. A significant correlation between DE miRNAs and mRNAs and clinical parameters (i.e., antiphospholipid antibodies, serum creatinine, estimated glomerular filtration, proteinuria, and serum cholesterol) has been detected. Based on our data, we propose that DE miRNAs and their downstream network may be involved in MGN pathogenesis and could be considered as potential diagnostic biomarkers of MGN.